The detection of the level of analytes, such as glucose, lactate, oxygen, and the like, in certain individuals is vitally important to their health. For example, the monitoring of glucose is particularly important to individuals with diabetes. Diabetics may need to monitor glucose levels to determine when insulin is needed to reduce glucose levels in their bodies or when additional glucose is needed to raise the level of glucose in their bodies.
Devices have been developed for continuous or automatic monitoring of analytes, such as glucose, in bodily fluid such as in the blood stream or in interstitial fluid. Some of these analyte measuring devices are configured so that at least a portion of the devices are positioned below a skin surface of a user, e.g., in a blood vessel or in the subcutaneous tissue of a user.
The user's comfort and the range of activities that may be performed while a portion of the device is positioned below a skin surface are important considerations in designing extended-use sensors for continuous or automatic in vivo monitoring of the level of an analyte, such as glucose. There is a need for a small, comfortable device which may continuously monitor the level of an analyte, such as glucose, while still permitting the user to engage in normal activities. Continuous and/or automatic monitoring of the analyte may provide a warning to the user when the level of the analyte is at or near a threshold level. For example, if glucose is the analyte, then the monitoring device might be configured to warn the user of current or impending hyperglycemia or hypoglycemia. The user may then take appropriate actions.
One of the challenges associated with producing an effective and comfortable monitoring device is securing an element of the monitoring device to the skin. A monitoring device element may be attached to the skin with an adhesive. However, adhesives eventually lose their adhesive properties. Also, outer layers of the skin continually slough off. Eventually, the loss of adhesion and sloughing off of the skin serve to detach the monitoring device element from the skin and the monitoring device element falls off of the user.
When the monitoring device element falls off of the skin, a new monitoring device element may have to be attached to the skin and a new sensor may have to be inserted into the skin. Accordingly, if a monitoring device falls off too quickly, its life is limited and a user must insert another sensor, adding to the cost of the monitoring device. Also, the more frequent insertions of sensors may cause skin trauma.
One manner of increasing the attachment time is to provide a stronger adhesive. However, increasing the strength of the adhesive makes removal of the monitoring device element from the skin more difficult and painful. Also, simply increasing the adhesive strength may not overcome the problems associated with outer layers of skin sloughing off the body. Accordingly, the present disclosure is directed to providing a structure and method of attaching an element of a monitoring device to a user's skin that will result in a longer-lasting attachment.